Drawing mandrel or plug



June 9, 1942. J. A. STAPLES ET AL DRAWING-MANDREL OR PLUG Filed June 9, 1941 2 Sheets-Sheet l TANNIE LEWIN JOHN A. STAPLES AITORNEY June 9, 1942. J. A. STAPLES ETAL DRAWING-MANDREL OR PLUG 2 Sheets-Sheet 2 Filed June 9, 1941 INVENTORS JOHN A. S PLES TAN NI E WIN ATTORNEY mary object the provision in Patented Julie 9, 1942 John A. Staples, University Lewin, Clayton, Mo., asslgnors Company, East St. Louis, 11L,

Delaware City, and Tannle to I'iewin-Mathes a corporation of Application June 9, 1941, Serial No. 397,221

Claims.

This invention relates generally to the production of seamless tubing and, more particularly, to a certain new and useful improvement in drawing-mandrels or plugs for the cold drawing production of tubing.

In present conventional cold drawing practice, so far as we are aware, .the tubing which is to be drawn is sleeved or strung over a drawingmandrel or so-called plug which is supported on a relatively long plug-rod or holding-up bar until the swaged or so-called pointed end of the tubing comes into engagement with the forwardly presented end of the drawing-mandrel. The plug-rod or bar is then impelled forwardly under the bias of a heavy spring or other shifting structure for projecting the pointed end .of the tubing through the drawing-die for engagement by the jaws of the drawingcarriage.

In such practice, loss of time and material, as

' well as damage to tools and machinery, has resulted by reason of a tendency for the pointed end of the tubing to crack or break off as the tubing initially enters the die at the beginning of the second or further drawing operation on the same point. In addition, for some now unexplained reason, a very noisy vibratory quivering action, commonly referred to as chattering, is frequently encountered as the tubing is pulled through the die, resulting in accelerated break-down of the tools, as well as producing non-uniformity and impairing ridges or surface markings in and upon the inner and outer periphery of the finished tubing.

Our present invention has hence for its pricold drawing apparatus of a mandrel or plug so uniquely formed and constructed as to eliminate cracking or breaking-off of the pointed ends of tubing as the tubing enters the drawing-die and also obviate chattering with all its attendant and resulting defects in the finished tubing.

And with the above and other objects in view, our invention resides in the novel featuresof form and construction of the drawing-mandrel or plug presently described and pointed out in the claims. 1

In the accompanying drawings (two sheets):

Figure 1 is aperspective 'view of a drawingbench comprising a plug-rod or holding-up bar equipped with a drawing-mandrel or plug constructed in accordance with and embodying our present invention;

Figure 2 is a perspective view of a primary drawing plug adapted for use in the first pass or draw to which the tubing is subjected;

Figure 3 is a perspective view of a secondary drawing-plug of all successive passes or draws to which the tubing is subjected;

Figure 4 is a diagrammatic view illustratingthe primary stage in cold drawing operations employing the primary drawing-plug of Figure 2;

and

' Figures 5, 6, 7, 8, and 9 are progressive diagrammatic views of successive stages in cold drawing operations employing drawing-mandrels or plugs of our invention.

Referring now in more detail and by reference characters to the drawings, which illustrate a preferred embodiment of the present invention, A designates a conventional drawing-bench,'suitably located upon which is a rigid mounting I for a removable or renewable drawing-die 2. Mounted for travel on the bench A, is a drawcarriage 3 provided with suitable jaws 4 for gripping the tube T or other work at its pointed end t and having means for engagement with an endless traveling draw-chain 5 for pulling movement of the carriage 3 and gripped tube T along the bench A and away from the die 2 during a drawing operation. Extending rearwardly from the die-mounting l, is a pair of horizontally disposed guide-rods 6 fixed at their rear end in a support I and supported intermediate their endsby a plurality of spaced intermediate'plates or the like 8 and preferably connected by arcuate cross tie-members 9.

Mounted on the support I in axial alignment with the die 2, is a plunger-cylinder l0 connected by. means of suitable pipes or conduits H in a hydraulic system (not shown), in which is included a suitable control valve positioned for convenient manipulation by the machine-operator.

Working in the cylinder fixed at an end to the III, is a piston l2, and piston I2, is an outwardly extending piston-rod I3 connected at its other or outer end to a rod orbar l4 suitably elongated to extend at its free end forwardly intermediate the rods 6 and over the supports or plates 8 to a point adjacent the drawing-die 2, the rod or bar M at such extremity being formed or provided with a tapped chamber or socket, as at M, for interchangeable connection with drawing-plugs or mandrels B, B.

The so-called primary mandrel or plug- B adapted for use in the initial passor draw is dimetrally sized for complementary drawing coaction with the initial drawing-die 2 and consists of an accurately turned cylindrical section l5 of our invention adapted for use in I an annular steel and preferably hardened tool steel formed or provided at one end with an accurately "machined co-axial threaded shank l6 diametrally sized for snugfitting engagement in the socket l4 of the rod or bar l4. At its opposite end, the cylindrical plug-section I5 is preferably slightly chamfered clrcumferentially, as at I1, and provided with a fiat end face l8.

In the initial draw or pass, the cylinder I is hydraulically retracted so as to shift the rod l4 and its associated plug B rearwardly away from the die 2. The raw tube I, having been swaged in a conventional swaging machine (not shown) in the formation of a so-called pointed end t, is suitably fed or. strung over the plug B and the rod or bar I4 until the inner oblique face of the pointed tube-end t comes into impinging engagement with the chamfered margin ll of the plug B and is positioned in registering alignment with the entrant end of the die 2, substantially in the manner shown in Figure 4.

The cylinder l0 and its associated piston l2 are then hydraulically actuated to shift the rod or bar I 4, together with the plug B and the supported tube-section T, forwardly, pointed-end t of the tubing T through the die 2 for engagement in and by the draw-carriage jaws 4 and positioning the plug B for tube-reducing or drawing co-operation with media 2, wherethe pointed tube-end t being securely gripped by the draw-carriage jaws 4, the drawcarriage 3 is engaged with the draw-chain and pulled forwardly, thereby drawing the section of tubing T through the die 2 and over the plug B.

At the beginning of this initial drawing operation, the plug B moves forwardly under the influence of the piston l2 and concurrently with the movement of the tube T until, as stated, the plug B is co-operatively located with respect to the die 2. Momentarily, therefore, the annular space between the plug B and the die 2 is greater than the ultimate desired thickness to which the tubing T is being reduced, withthe result that shoulder, ridge, or ledge, commonly termed a collar, s is formed in the pointed tubeend it, all as best seen in Figure5. It will, of course, be understood that such first drawing operation is repeated, the same or asimilar plug B and die 2 being used or employed for each successive section of the tubing making up the particular batch of tubing being run at any one time.

When the initial draw or pass has been completed on the entire run of tubing, the plug B and die 2 are removed from the rod or bar l4 and diesupporting plate 1, respectively, and replaced by a secondary plug-die set B, 2; or the first drawn tube-sections may be suitably transported or conveyed to a section bench equipped with a plug-die set B, 2'.

The die 2 is substantially conventional and in all respects to the die 2, except reduction in inner diametral size. The plug B, however, is precisely machined from suitable hardened tool integrally includes a cylindrical body section l5 having an external diametral size precisely equal to the desired internal diametral size to which the tubing section T isto be reduced during the second pass or draw. Extending co-axially from one end of the cylindrical section I5, is an externally threaded shank l6 substantially identical in all respects to the shank I6 of the primary plug B.

Extending co-axially from the opposite end of the plug body-section. I 5', is a preferably cylinprojecting the reduction in diameter drical diametrally reduced extension or so-called length and diameter-so related taper of the pointed tube-end t latter is strung or sleeved over incident to the nose -ll having a to the degree of that, when the the plug B collar s will pass through the any reduction in wall thickness in the manner of a so-called nodie 2 without that is to plug draw."

The hydraulic cylinder III is again actuated a) ttile rod or bar [4, together with the plug an i periphery of the tubing at a point spaced rearwardly from the first shoulder or collar s, all as best seen in Figure 7.

If desired, a tertiary be provided,

set B, 2', except, again, for reduced size, the tubing being worked being accordingly further reduced in diameter and wall-thickness and in the draw being provided upon cry with a third shoulder or collar s", as indicated in Figure 9.

Should it be desired to subject the tubing section T to further successive passes for further and wall thickness, additional plug-die sets of suitable relative size will be substituted or employed, each set being likewise substantially similar to the set B, 2, and in each case the, respective plugs B are provided with forwardly projecting noses or extensions l9 so shaped and sized as to, when in impinging engagement with the pointed and t of the tubing being worked or reduced, locate the cylindrical body-portion l5 of the particular plug for engaging the inner wall of the tubing section T its inner periphparting from the nature and principle of our invention.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. A seamless tube drawing-mandrel integrally including a substantially cylindrical bodysection and a diametrically reduced cylindrical nose-portion projecting forwardly from the body-section for impinging engagement at its free-end margin with the pointed end of a tubing-section being drawn for preventing engagement of the body-section with such tubing-section during the initial die-positioning of the mandrel for a drawing operation.

2. A seamless tube drawing-mandrel constructed of hardened tool steel and integrally including an accurately turned cylindrical bodysection having an internal diametrical size to which the tubing is to be reduced and a diametrically reduced cylindrical nose-portion projecting forwardly from the body-section and elongated for impinging engagement at its free end margin with the pointed end of a tubingsection being drawn for preventing engagement of. the body-section with such tubing-section during the initial die-positioning of the mandrel for a drawing operation.

3 A seamless tube drawing-mandrel integrally including an accurately turned cylindrical body-section having an internal diametrical size to which the tubing is to be reduced ahd a diametrically reduced cylindrical nose-portion projeoting forwardly from the body-section and having a. length such that a tubing-shoulder resulting from a previous pass .to which the tubing has been subjected will be disposed'intermediate the free margin of the nose-portionand the forward end of thebody-section when the mandrel is positioned within eration.

4. A seamless tube drawing-mandrel integrally including an accurately turned cylindrical body-section having an internal diametrical size to which the tubing is to be reduced and a diametrically reduced cylindrical nose-portion projecting forwardly from the body-section and having a length in relation to its diameter such that a tubing-shoulder resulting from a previous pass to which the tubing has been subjected will be disposed intermediate the free margin of the nose-portion and the forward end of the bodysection when the mandrel is positioned within the tubing for a drawing operation.

5. A seamless tube drawing-mandrel constructed of hardened tool steel and integrally including an accurately turned cylindricalbodysection having an internal diametrical size to which the tubing it to be .reduced and a dia-' metrically reduced cylindrical nose-portion projecting forwardly from the body-section and having a length and diametrical size for impinging engagement at its free-end margin with a tubing-section being drawn for spacing such tubing-sectionat its inner face from said bodysection as the pointed end of the tubing-section initially comes into engagement with a companion die. e

' JOHN A. STAPLES. TANNIE LEWIN.

the tubing for a drawing op- I 

